#include<iostream>
#include<vector>
#include<queue>
#include<cstring>
#include<cmath>
#include<map>
#include<set>
#include<cstdio>
#include<algorithm>
#define debug(a) cout<<#a<<"="<<a<<endl;
using namespace std;
const int maxn=200;
typedef long long LL;
inline LL read(){LL x=0,f=1;char ch=getchar();	while (!isdigit(ch)){if (ch=='-') f=-1;ch=getchar();}while (isdigit(ch)){x=x*10+ch-48;ch=getchar();}
return x*f;}
char a[maxn];
int main(void)
{
  cin.tie(0);std::ios::sync_with_stdio(false);
  LL t;cin>>t;
  while(t--){
    LL n,k;cin>>n>>k;
    cin>>(a+1);
    if(k==0){
        cout<<"YES"<<"\n";
    }
    else{
        LL l=1;LL r=n;LL cnt=k;
        if(n<=k*2){
            cout<<"NO"<<"\n";
            conwtinue;
        }
        bool flag=1;
        while(l<r){
            if(a[l]==a[r]) l++,r--,cnt--;
            else if(a[l]!=a[r]){
                flag=0;
                break;
            }
            if(cnt==0) break;
        }
        if(flag==1){
            cout<<"YES"<<"\n";
        }
        else cout<<"NO"<<"\n";
    }
  }
return 0;
}
